JP2005344114A - Sterically hindered reagent for use in single component siloxane cure system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an economic single component addition-curing polysiloxane system capable of elongating a pot life after mixing to enable the treatment in an industrially feasible embodiment. <P>SOLUTION: The single component addition-curing polysiloxane system includes a siloxane reagent that has at least one unsaturated organic functional group for crosslinking reaction, a crosslinking reagent that has a silicon hydride group for crosslinking, and a catalyst. Either the unsaturated functional group of the siloxane reagent, the silicon hydride group of the crosslinking reagent, or both are sterically hindered. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to siloxane polymers, and more specifically to addition cure systems for siloxane polymers.

  Siloxane polymers (also known as “silicone” polymers) are stable polymers used in many different applications. Siloxane polymers can be produced by a variety of reaction mechanisms, which are generally divided into two classes: solvent systems (dispersions of high molecular weight solids) and room temperature cure (RTV) types. RTV materials are further divided into RTV-I and RTV-II categories. RTV-I cures when exposed to water and is typically a one-part system. RTV-II is typically a two-part formulation and generally can be cured at room temperature when all ingredients are mixed. RTV-II is known as an addition curing (or addition crosslinking) mechanism. In addition cure systems, the siloxane material is crosslinked by the reaction (hydrosilylation) of aliphatically unsaturated groups in the polyorganosiloxane with Si-bonded hydrogen in the presence of a catalyst, typically a platinum compound. As soon as the essential components are mixed together, the crosslinking reaction starts immediately. Therefore, addition-cured silicones are almost exclusively prepared as two-part formulations, and the crosslinkers silicon hydride (SiH) and aliphatic to allow control over when product formation occurs. The siloxane having an unsaturated functional group is separated.

  Two-part addition crosslinkable siloxane materials have certain disadvantages such as post-treatment, additional handling and mixing steps, and the need for additional manufacturing equipment. Also, after mixing the separate components, the material has a limited pot life at room temperature. This requires, for example, short processing after mixing, quality control of additional mixing steps, frequent cleaning of storage containers, metering devices and processing devices. This is because the remaining material can harden / gel and adhere to the container wall.

  Because of these disadvantages, many attempts have been made to provide addition crosslinkable silicone materials as a one-part system. Since all the components required for crosslinking exist together, various methods for suppressing early crosslinking have been studied. Currently, inhibitor compounds that inhibit catalytic activity are used and can be added to increase the pot life of the addition crosslinkable material system. Although pot life can be increased as desired through the type and content of such inhibitors, the use of such inhibitors results in the need to use much higher onset temperatures since the crosslinking rate decreases at room temperature. Furthermore, the final product can result in undercrosslinking or a low degree of effect. In addition, the use of inhibitor compounds increases the cost of making siloxane materials, both by the cost of purchasing additional components and by additional handling and processing steps.

  Other attempts for one-part addition-cured siloxane systems include encapsulating the platinum catalyst in a protective coating that does not break until the mixture is heated. Such systems have been found to be expensive and the catalyst is not homogeneously distributed in the mixture, reducing efficiency.

  Thus, there is a need for a one-part addition-cured polysiloxane system that can extend the pot life after mixing so that it can be processed in an economical and industrially feasible manner.

  In one aspect, the present invention comprises a siloxane reactant having at least one unsaturated organic functional group for a crosslinking reaction, a crosslinking agent comprising a silicon hydride group for said crosslinking reaction, And a one-component addition-curable polysiloxane system in which at least one or both of the unsaturated organic functional group and the silicon hydride of the crosslinking agent are sterically hindered. The one-part addition curable polysiloxane system also includes a catalyst.

  In another aspect, the invention includes a method of making a polysiloxane polymer by one-component addition curing. The method includes mixing a siloxane reactant comprising a siloxane polymer having functional groups for cross-linking, a cross-linking agent comprising silicon hydride functional groups for cross-linking and a catalyst into a one-part mixture, wherein the siloxane At least one or both of the functional groups of the reactants and the silicon hydride of the crosslinker are sterically hindered. A crosslinking reaction between the siloxane reactant and the crosslinking agent is performed, wherein the sterically hindered functional group has a crosslinking reaction rate compared to the comparative crosslinking reaction rate of the comparative non-sterically hindered siloxane and the non-sterically hindered crosslinking agent. Reduce.

  In yet another aspect, the present invention is a method of manufacturing a sensor film comprising a siloxane reactant having a functional group for cross-linking, a cross-linking agent including a silicon hydride functional group for cross-linking, a catalyst, and a plurality of conductive materials. Mixing the functional particles together to form a matrix mixture, wherein at least one or both of the functional groups of the siloxane reactant and the silicon hydride of the crosslinker are sterically hindered. The method further includes reacting the siloxane reactant and the cross-linking agent in a cross-linking reaction, wherein the sterically hindered functional group of at least one or both of the siloxane reactant and the cross-linking agent is non-reactive in the comparative siloxane. Compared to the crosslinking reaction rate between the sterically hindered functional group and the non-sterically hindered silicon hydride functional group of the crosslinking agent, the crosslinking reaction rate is decreased. The matrix mixture is applied onto the sensor probe to produce a polysiloxane matrix product.

  The compositions and methods of the present invention have advantages over siloxane addition cure system compositions known in the art, including one or more of the following advantages. That is, with reduced initial cross-linking reaction rate, improved efficiency by eliminating the two-part curing system, improved control of the cross-linking process, improved processability, industrial efficiency, and the performance of addition-curing siloxane systems is there. Further uses, advantages and embodiments of the present invention will be apparent from the description herein.

  The following definitions and non-limiting guidelines must be considered when considering the description of the invention described herein. The headings and subheadings used herein (eg, <polysiloxane polymer product>, <siloxane reactant>, <crosslinker>, <catalyst>, <additional component>, <method>) are disclosed in the present invention. Are not intended to limit the disclosure of the invention or its aspects, in particular, “technical field”, “background art”, and May include technical aspects within the scope of and may not constitute an enumeration of prior art. The subject matter disclosed in “Solutions” is not an exhaustive or complete disclosure of the invention or its full scope. The classification or description of a material within a section of this specification as having a particular utility is made for convenience, and the material is used in any composition. Inferiority should not be derived from the fact that it must or must function according to its classification.

  Citation of references herein does not admit that they are prior art or related to the patentability of the invention disclosed herein. The description of a reference cited in “Background” is intended only to provide a general summary of allegations made by the author of the document, and is intended to ensure the accuracy of the content of the document. It is not an admission. References cited after “Disclosure of the Invention” in this specification are hereby incorporated by reference in their entirety.

  The description and specific examples, while indicating embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. Furthermore, the recitation of a plurality of aspects having the described features is not intended to exclude other aspects having additional features or other aspects that include different combinations of the described features.

  As used herein, the terms “preferred” and “preferably” refer to an embodiment of the invention that provides a benefit under certain circumstances. However, other embodiments may be preferred in the same or different situations. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the invention.

  As used herein, the word “comprising” and its derivatives are not intended to exclude other similar items where the listing of items in a list may be equally useful for the materials, compositions, devices and methods of the present invention. It is intended to be non-limiting.

  All composition percentages used herein are by weight of the total composition unless otherwise indicated.

  “About”, when used on a numerical value, indicates that the calculation or measurement allows some inaccuracy in the numerical value (approach to the accuracy in the numerical value, approximately or reasonably close to the numerical value). Is. If for any reason the inaccuracy caused by “about” is not understood in the ordinary sense in the art, “about” as used herein indicates that variations in numerical values up to 5% are possible. Is.

  The present invention provides a one-part curing system for producing a siloxane polymer product. Curing systems that introduce all of the reactants simultaneously in substantially a single step are generally known in the art as one-component or single component curing systems. One aspect of the present invention is the reduced reaction rate for the cross-linking / curing reaction that allows for a one-part curing system. The reduced reaction rate is greater for processing than previously possible with prior art curing systems (ie, siloxane reactants, crosslinkers or both functional groups are not sterically hindered). Means a longer duration.

Thus, the present invention comprises a siloxane reagent having at least one unsaturated organic functional group for a crosslinking reaction, a crosslinking agent comprising a silicon hydride functional group for the crosslinking reaction, and a catalyst, Provided is a one-part addition curable polysiloxane system in which at least one or both of the unsaturated organic functional group of the siloxane reactant and the silicon hydride functional group of the crosslinker are sterically hindered. Although the mechanism by which the present invention operates is not limited, the unsaturated organic functional group, the silicon hydride functional group, or the steric hindrance functional group on both, is a Si—H bond of silicon hydride or CH═ of unsaturated vinyl group. It is believed that it provides a steric bulk through side groups near the CH ₂ bond, which creates an energy activated barrier that reduces the cross-linking reaction rate. This slower reaction rate thus allows for the simultaneous combination of the component materials and subsequent processing of the component materials with a significant duration. This is a traditional two-part system (with non-sterically hindered reactants) where the cross-linking reaction is too fast to allow final delay in processing and mixing before producing the final polysiloxane product. In contrast to Thus, according to the principles of the present invention, the one-part curable polysiloxane system can be processed and handled for a significant amount of time after the components are mixed together, which means that the two-part system and the accompanying mixing and processing system. By providing a significant manufacturing benefit.

<Polysiloxane polymer product>
The addition cure system of the present invention preferably produces a polysiloxane polymer product. As used herein, “polysiloxane” generally refers to a structural repeating unit— [O—Si (RR ′) _n ] — (wherein R and R ′ are the same or different side groups ( silicon having an organic side constituent group, which can be the same or different, and can be a side constituent group, and n can be two or more values indicating repeats of structural repeat units (SRU) in the polymer backbone) It refers to a crosslinked polymer having an oxygen basic skeleton. SRU is one means of expressing the polymer structure of a polymer of unspecified length, generally a canonical substitution nomenclature (here, as recognized by those skilled in the art, multivalent groups are generally “poly” Reference is made to one or more polyvalent groups of (preface). Furthermore, siloxane polymers are also known in the art as “silicone” polymers. Preferred siloxane polymers are cross-linked and include homopolymers and copolymers. The term “copolymer” generically refers to a polymer structure having two or more monomers polymerized to each other, including polymers such as terpolymers having three linked monomers. “Homopolymer” refers to a polymer composed of a single monomer. The siloxane polymer may be, for example, a nominal SRU formula-[O-Si (RR ')) _n- (O-Si (R "R'")) _m ] (where R and R 'are R " And polyheterosiloxanes that may be of different side groups and / or different structural repeat units (having different side constituent groups), such as different side groups from R ′ ″. Further, R and R ′ can be different from each other, and the same is true for R ″ and R ′ ″.

  As explained above, the polysiloxane polymer product according to the present invention preferably has an addition cure mechanism in which the crosslinking reaction is caused by an addition reaction (hydrosilylation) of the hydride functionalized crosslinking agent to the vinyl group of the siloxane reactant. This reaction is typically facilitated by a metal catalyst or metal catalyst complex.

<Siloxane reactant>
According to one aspect of the invention, a “siloxane reactant” is generally defined as a siloxane polymer having at least one unsaturated organic functional group for reacting with a crosslinking agent in a crosslinking reaction. The siloxane reactant polymer can be a structural repeating unit— [O—Si (RR ′) _n ] —, where R and R ′ can be the same or different side constituent groups, where n is Having a basic backbone of silicon and oxygen with organic side constituent groups that may be the same or different, generally described by (which may be two or more values indicating the number of SRU repeats in the polymer backbone). In the siloxane reactant polymer, it is preferred that at least one side constituent group is a functional group capable of reacting in a subsequent crosslinking reaction. In certain preferred embodiments of the present invention, the siloxane polymer has an unsaturated organic functional group for crosslinking with hydride groups by a hydrosilylation mechanism, and this unsaturated functional group is generally an alkene or alkyne such as Corresponds to a hydrocarbon functional group containing a saturated carbon-carbon bond. A preferred functional group in the siloxane reactant is an unsaturated alkene having a vinyl group containing a carbon-carbon double bond. That is, an example of a useful siloxane reactants in the present _{invention, SRU [-O-Si (CH} 3) (CHCH 2) - ( wherein, R ¹ is an ethyl group containing a vinyl group (HC = CH ₂₎ And R ² is a methyl group (CH ₃ ). In one embodiment of the invention, the siloxane reactant is added to the one-part curing system as a non-sterically hindered siloxane reactant, where the unsaturated organic functional group is non-sterically hindered. In such an embodiment, it is preferred that at least a portion of the crosslinker silicon hydride is sterically hindered.

  In another embodiment of the invention, the unsaturated organofunctional group of the siloxane reactant is sterically hindered. By “steric hindrance” is meant that the steric effect resulting from the crowding of substituents on the molecule near the silicon atom in the silicon-carbon bond of the vinyl group occurs in the molecule. In particular, the steric effect is recognized as a change in steric energy between the reactant and the product, and this is understood as a change in the reaction rate. In the present invention, the desired steric effect is steric reduction or hindrance. The impact of steric hindrance on reactivity is divided into three main types of effects. Induction (polarization), resonance and steric. In most cases, two or three of these effects act within the molecular structure to promote steric hindrance and accurately identify which of these three effects affects the observed change in reaction rate Difficult to do. Although not limiting the mechanism by which the present invention operates, physically large or bulky substituents are adjacent in the same silicon atom (the same silicon atom bonded to a functional group for crosslinking) or in the crosslinker molecule. When attached to a silicon atom, it is generally believed that bulky groups physically inhibit external reactive groups from accessing reactive functional groups, resulting in reduced reaction rates. In addition, bulky groups can alter the reactivity of reactive functional groups (eg, vinyl groups) through induction or resonance. In accordance with the principles of the present invention, the rate of the cross-linking reaction is significantly reduced, thus extending the time available for processing after mixing the reaction components.

According to one aspect of the invention, a siloxane reactant having a sterically hindered unsaturated organic functional group is incorporated into a silane (having a skeleton of bonded silicon atoms) or a siloxane (having a skeleton of alternating silicon-oxygen atoms). be able to. In one embodiment, the SRU for the sterically hindered unsaturated organic (vinyl) group of the siloxane reactant has a nominal general formula:

Where R ¹ and R ² each contain a non-reactive bulky organic substituent. “Bulky” means that the organic group contains 3 or more carbon atoms. In some embodiments, bulky groups contain no more than about 20 carbon atoms. In various embodiments, the organic group contains 3-20, 4-15, or 5-10 carbon atoms. The organic group is preferably non-reactive, i.e., has no reactivity to interfere with or react with the functional group of the siloxane reactant. R ¹ and R ² are preferably selected independently of each other. In some embodiments, R ¹ and R ² are distinct and are different organic groups, and in other embodiments, R ¹ and R ² are the same organic group.

R ¹ and R ² are preferably selected from the group consisting of substituted or unsubstituted linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof. Particularly preferred non-reactive organic groups include propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, alkylphenyl, cyclopentyl and phenylpropyl. When the bulky organic groups R ¹ and R ² are substituted, the side constituent groups can be, for example, fluorine, chlorine, bromine, oxygen, nitrogen or sulfur as long as the organic group remains non-reactive with the siloxane. Can contain polar atoms or molecules such as Examples of such non-reactive substituted bulky organic groups include butylated aryloxypropyl, N-pyrrolidone propyl, cyanopropyl, benzyltrimethylammonium chloride, and hydroxyalkyl.

Further, R ³ , R ⁴ and R ⁵ are each independently selected from the group consisting of a non-reactive organic group and hydrogen. As will be appreciated by those skilled in the art, depending on the desired rate of reaction and system design, when R ⁴ is selected to be hydrogen, R ³ and R ⁵ are bulky non-reactive as described above. Another sterically hindered hydride can be provided on the difunctional silicon molecule, or on the more traditional smaller organic group that can promote the overall crosslinking rate, which can be selected to be an organic group.

In another embodiment of the invention, the sterically hindered hydride has the formula:

(Wherein the skeleton of the molecule is silane, and R ¹ and R ² include a non-reactive organic group having 3 or more carbon atoms). In some embodiments, the non-reactive organic group contains no more than about 20 carbon atoms. In some embodiments, bulky organic groups contain no more than about 20 carbon atoms. In various embodiments, the organic group contains 3-20, 4-15, or 5-10 carbon atoms. R ¹ and R ² are independently selected from each other as described in the embodiment immediately above and are selected from the group consisting of substituted and unsubstituted linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof. You can choose. Similarly, R ³ , R ⁴ and R ⁵ are independently selected from the group consisting of non-reactive organic groups and hydrogen.

Furthermore, as shown in the previous two embodiments, the hydride functionality can be incorporated at the end of the molecule or within the molecular backbone. Thus, in another embodiment, the sterically hindered hydride is located at the end of the molecule in the crosslinker and has the general formula:

Wherein R ¹ and R ² include non-reactive organic groups having 3 or more carbon atoms. In some embodiments, the non-reactive organic group contains no more than about 20 carbon atoms. In some embodiments, the bulky non-reactive organic group contains no more than about 20 carbon atoms. In various embodiments, the organic group contains 3-20, 4-15, or 5-10 carbon atoms. Selection of R ¹ and R ² are the same as those described in embodiments of the above, R ¹ and R ² are independently substituted and unsubstituted linear alkyl, branched alkyl, aryl, aromatic, and Selected from the group consisting of mixtures thereof. In addition, each respective R ³ and R ⁴ is independently selected from the group consisting of non-reactive organic groups and hydrogen. In this embodiment, the bulky organic substituent provides hydride physical blocking, whether attached to the same silicon atom to which the hydride is attached.

  As will be appreciated by those skilled in the art, any of the previously described embodiments for the sterically hindered unsaturated organic functional group of the siloxane reactant molecule may be mixed together to ultimately form a siloxane reactant that reacts with the silicon hydride functional group of the crosslinker. A mixture of different molecules can be made. Furthermore, depending on the system design, more traditional siloxane reactants (non-sterically hindered siloxane reactants) can be added at low concentrations to the sterically hindered siloxane reactant to accelerate the crosslinking reaction rate. As will be appreciated by those skilled in the art, at least a portion of the siloxane reactant having an unsaturated organic functional group, at least a portion of the cross-linking agent having a silicon hydride functional group, or both have a sterically hindered functional group. This can then be used to optimize the crosslinking reaction rate. Preferably, the siloxane reactant is added to the one-part curing system at a concentration of about 1 to about 75 percent of the total weight (excluding fillers and additives).

  Incorporation of bulky non-reactive organic side groups into the siloxane reactant molecule is accomplished by polymerization conducted in a conventional manner, as will be appreciated by those skilled in the art. Silicone molecules having two bulky side groups in the vicinity of the vinyl group are preferably reactive functional groups (e.g., to facilitate incorporation into the silicone-based backbone by polymerization as in the usual manner). Epoxy, amine, mercapto, methacrylate / acrylate, acetoxy, chlorine, hydride or vinyl, or hydroxyl groups). After introducing bulky non-reactive side groups into the molecule, the newly generated sterically hindered unsaturated organic functional group can act as a siloxane reactant in an addition cure one-part system.

<Crosslinking agent>
Crosslinking by addition curing (eg, hydrosilylation) requires a crosslinking (curing) agent in addition to the siloxane reactant. The cross-linking agent preferably reacts with accessible functional groups on at least a portion of the unsaturated functional side groups within the siloxane reactant. In certain embodiments of the invention, preferred crosslinkers include cross-linking compounds that include sterically hindered silicon hydride functional groups.

According to certain embodiments of the invention, crosslinkers having sterically hindered silicon hydrides can be incorporated into silane (having a skeleton of bonded silicon atoms) or siloxane (having a skeleton of alternating silicon-oxygen atoms). In one embodiment, the SRU for the sterically hindered hydride of the crosslinker is of the nominal general formula:

Where R ¹ and R ² each contain a non-reactive bulky organic substituent. “Bulky” means that the organic group contains 3 or more carbon atoms. In some embodiments, bulky groups contain no more than about 20 carbon atoms. In some embodiments, bulky groups contain no more than about 20 carbon atoms. In various embodiments, the organic group comprises 3-20, 4-15, or 5-10 carbon atoms. The organic group is preferably non-reactive, i.e., has no reactivity to interfere with or react with the functional group of the siloxane reactant. R ¹ and R ² are preferably selected independently of each other. In some embodiments, R ¹ and R ² are distinct and are different organic groups, and in other embodiments, R ¹ and R ² are the same organic group.

R ¹ and R ² are preferably selected from the group consisting of substituted or unsubstituted linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof. Particularly preferred non-reactive organic groups include propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, alkylphenyl, cyclopentyl and phenylpropyl. When the bulky organic groups R ¹ and R ² are substituted, the side constituent groups are, for example, fluorine, chlorine, bromine, oxygen, as long as the organic group remains non-reactive with the siloxane functional group. It can contain polar groups or molecules such as nitrogen or sulfur. Such non-reactive substituted bulky organic groups include butylated aryloxypropyl, N-pyrrolidone propyl, cyanopropyl, benzyltrimethylammonium chloride, and hydroxyalkyl.

Further, R ³ , R ⁴ and R ⁵ are independently selected from the group consisting of non-reactive organic groups and hydrogen. As will be appreciated by those skilled in the art, depending on the desired rate of reaction and system design, when R ⁴ is selected to be hydrogen, R ³ and R ⁵ are bulky non-reactive as described above. Another sterically hindered hydride can be provided on the difunctional silicon molecule, or on the more traditional smaller organic group that can promote the overall crosslinking rate, which can be selected to be an organic group.

In another embodiment of the invention, the sterically hindered hydride has the formula:

(Wherein the skeleton of the molecule is silane, and R ¹ and R ² include a non-reactive organic group having 3 or more carbon atoms). In some embodiments, the non-reactive organic group contains no more than about 20 carbon atoms. In some embodiments, bulky organic groups contain no more than about 20 carbon atoms. In various embodiments, the bulky organic group comprises 3-20, 4-15, or 5-10 carbon atoms. R ¹ and R ² are selected independently from each other as described in the embodiment immediately above, and are within the group consisting of substituted and unsubstituted linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof. You can choose from. Similarly, R ³ , R ⁴ and R ⁵ are independently selected from the group consisting of non-reactive organic groups and hydrogen.

Furthermore, as shown in the previous two embodiments, the hydride functionality can be incorporated at the end of the molecule or within the molecular backbone. Thus, in another embodiment, the sterically hindered hydride is located at the end of the molecule in the crosslinker and has the general formula:

Wherein R ¹ and R ² include non-reactive organic groups having 3 or more carbon atoms. In some embodiments, the non-reactive organic group contains no more than about 20 carbon atoms. In some embodiments, the bulky non-reactive organic group contains no more than about 20 carbon atoms. In various embodiments, the organic group contains 3-20, 4-15, or 5-10 carbon atoms. Selection of R ¹ and R ² are the same as those described in embodiments of the above, R ¹ and R ² are independently substituted and unsubstituted linear alkyl, branched alkyl, aryl, aromatic, and Selected from the group consisting of mixtures thereof. In addition, each respective R ³ and R ⁴ is independently selected from the group consisting of non-reactive organic groups and hydrogen. In this embodiment, the bulky organic substituent provides hydride physical blocking, whether attached to the same silicon atom to which the hydride is attached.

  As will be appreciated by those skilled in the art, any of the previously described embodiments for sterically hindered silicon hydride molecules can be mixed together to create a mixture of different molecules that constitute a crosslinker that reacts with the unsaturated functional groups of the siloxane reactant. Can do. Furthermore, depending on the system design, more traditional crosslinkable silicon hydride compounds (non-sterically hindered silicon hydride compounds) can be added to the crosslinker at low concentrations to accelerate the crosslinking reaction rate. The percentage of hydride functionality in the crosslinker molecule of the present invention can range from about 2% to about 98%. However, a preferred percentage of hydride functional groups in the crosslinker molecule is from about 2 to about 45%. Preferably, the crosslinker is added to the one-part curing system at a concentration of about 1 to about 75 percent of the total weight (excluding fillers and additives).

  As will be appreciated by those skilled in the art, the silicon hydride used in the one-part addition-cured polysiloxane system can be a traditional non-sterically hindered silicon hydride molecule, which is converted to a sterically hindered siloxane reactant (sterically hindered unsaturated organic functional group). Can be combined with

  Incorporation of bulky non-reactive organic side groups into the silicon hydride molecule of the crosslinker of the present invention is accomplished by polymerization performed in a conventional manner, as will be appreciated by those skilled in the art. Silicone molecules having two bulky side groups in the vicinity of the hydride group are preferably reactive functional groups (e.g., to facilitate incorporation into a silicone-based backbone by polymerization, such as by conventional methods). Epoxy, amine, mercapto, methacrylate / acrylate, acetoxy, chlorine, hydride or vinyl, or hydroxyl groups). After introducing bulky non-reactive side groups into the molecule, the newly generated sterically hindered silicon hydride can act as a crosslinker in an addition cure one-part system.

Examples of sterically hindered hydrides useful in the present invention include the nominal general SRU formula:

(Here, the skeleton of the molecule is silane, R ¹ and R ² bulky organic groups are selected as octyl groups, and R ³ , R ⁴ and R ⁵ are selected as non-reactive methyl groups. Such sterically hindered crosslinkers are commercially available as 25-30% methylhydrosiloxane-octylmethylsiloxane copolymers available under the trade name HAM301 by PA, Gelest, Tarrytown. .

<Catalyst>
The curing system according to the present invention further includes a catalyst for promoting the hydrosilylation crosslinking reaction at each functional group site between adjacent siloxane and crosslinker chains. Preferred catalysts according to the present invention include ruthenium (Rh), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co) or mixtures thereof. The most preferred catalyst system includes Pt. A suitable catalyst system that can be used for hydrosilylation is, for example, a platinum carbonylcyclovinylmethylsiloxane complex used for enhanced curing, such as SIP6829, commercially available from Gerest, Inc .; (PPh ₃ ) ₃ RhCl or Rh (I) catalyst such as [(C ₂ H ₄ ) ₂ RhCl] ₂ , Ni catalyst, (PPh ₃ ) ₃ RdCl ₂ , Rh ₂ (OAc) ₄ , Ru ₃ (CO) ₁₂ , Co ₂ ( CO) ₈ or equivalent thereof. Preferably, the catalyst is formulated into the one-part curing system mixture at about 0.05 to 1% by weight of the total mixture (excluding filler particles or other additives).

<Additional ingredients>
The present invention contemplates adding particles such as conductive particles or inorganic fillers, thus creating a matrix of polysiloxane material (resin) in which a plurality of particles are distributed. In addition, other compounds and additives known to those skilled in the art are often added to the polysiloxane compounds, and these compounds and additives are contemplated by the present invention. Such additional additives may include sterically hindered phenol antioxidants, for example, antioxidants such as Vanox SKT, Banox GT, Vanox 1320.

  One important aspect of the present invention is that all of the reaction components can be added together to process the material well enough after a one-part system. The handling and flowability of a one-part addition cure system depends on the rate of crosslinking after all reaction components (especially the catalyst) have been added. The degree of crosslinking related to the crosslinking reaction rate affects the viscosity of the mixture (the greater the degree of crosslinking, the higher the viscosity). The amount of time left for handling is commonly known as “pot life” and in a preferred embodiment of the invention, this pot life is 1 day (24 hours) or longer. In a particularly preferred embodiment, the pot life is 168 hours or more than a week. A preferred embodiment of the present invention provides a pot life that extends to multiple weeks or months. According to the present invention, the reaction rate delay is achieved mainly by the steric hindrance of the crosslinker silicon hydride.

<Method>
One method of producing the polysiloxane polymer product according to the present invention in one-part addition curing is to use a siloxane reactant having an unsaturated organic functional group for crosslinking, a crosslinking agent having a silicon hydride functional group for crosslinking, and Mixing the catalyst into a one-part mixture, wherein at least one or both of the functional groups of the siloxane reactant and the silicon hydride of the crosslinker are sterically hindered. A crosslinking reaction is performed between the siloxane reactant and the crosslinking agent. During this reaction, the sterically hindered functional group is compared to the comparative non-sterically hindered functional group of the siloxane and the non-sterically hindered silicon hydride functional group of the crosslinker (has a faster reaction rate due to the lack of steric hindrance). As compared to the rate of cross-linking reactions in a one-part system.

  The polysiloxane copolymer product is preferably formed at least about 24 hours after mixing. That is, the crosslinking reaction is preferably performed for at least about 24 hours after mixing. In some embodiments, the polysiloxane polymer product forms after 168 hours (1 week). By polysiloxane “product” is meant that the polysiloxane material is substantially complete in curing and is in a final cross-linked state (corresponding to a degree of cross-linking substantially similar to the desired% cross-linking). The final form of the product corresponds to a physical phase that can no longer be processed or processed in an industrially viable manner, and thus this physical phase is a substantially solid or semi-solid phase. . That is, the present invention allows the mixed one-part system to be processed and processed prior to production of the final polysiloxane. As explained above, the one-part system can be processed and processed for at least 24 hours in that it is in a semi-solid viscous phase that allows processing. This processable / processable mixture is processed by conventional processing means such as mixing, shearing, de-molding, coating (eg with a doctor knife), casting, lamination, extrusion, pad printing, spraying or silk screening.

  The cross-linking reaction rate depends on the degree of steric hindrance mainly related to the size of the adjacent bulky reactive substituents (the reaction rate decreases as the physical size increases). The reaction rate also depends on the temperature, and the crosslinking reaction is promoted when the temperature is increased. That is, the temperature can be used to control the reaction rate to match the processing requirements. Various embodiments of the invention perform the mixing and crosslinking reaction at ambient temperature. However, in another aspect, the temperature can be varied during production and processing to promote or reduce the reaction rate as desired. This can be particularly useful in embodiments where the activation energy is high for the reaction system, where the thermal energy serves to initiate the cross-linking reaction when desired. In this way, the addition cure system of the present invention provides “on-demand” cure that can be controlled by temperature. Generally, such curing / crosslinking temperatures range from about 30 ° C to about 250 ° C. Thus, in one embodiment, performing the curing or crosslinking step includes a curing initiation step that raises the temperature of the reaction component and catalyst mixture to effect curing.

  In another aspect of the present invention, when producing a polysiloxane matrix, a plurality of conductive particles are mixed into a one-part addition curing system. The plurality of conductive particles is added within a range of about 25 to about 75% of the total mixture, depending on particle characteristics such as tendency to disperse in the matrix. The conductive particles are preferably mixed well into the polymer mixture for uniform distribution. The polymer or matrix mixture can be, for example, a mixer (eg, a Banbury® or Brabender® mixer), a high speed mixer, a kneader, a single or twin screw extruder (eg, a single screw extruder or a twin screw extruder). Can be blended and mixed by a device known in the art such as

  Polysiloxane polymer films are useful as products in the technical field, such as polymer adsorption chemiresistor sensors, where the polymer film in the sensor is in an ambient atmosphere containing the analyte of interest (chemical compound). Exposed. A charge is applied to the polymer film. The polymer absorbs the analyte of interest, which results in a change in the volume of the film and hence a change in the electrical resistance of the film. In addition, conductive particles can be distributed in the polymer film to increase sensitivity to resistance changes in the material as the polymer volume changes. The mixture of all reaction components is applied to the sensor probe while it can still be processed. The mixture is preferably applied to the sensor surface by conventional application means (eg doctor blade, cast, lamination, extrusion, pad printing, spraying or silk screening).

  When using prior art siloxane addition cure systems, an unacceptable increase in resistance was observed, where there was a significant time lapse after mixing and before application of the matrix mixture to the sensor. This increase in resistance may be due to a harder (more viscous and highly cross-linked) polymeric material that may result in a poor interface with the sensor components. The present invention improves the performance of siloxane polymer matrix films in sensor probe environments. This matrix mixture can be processed longer after mixing the reaction components, thus improving the interface between the polymer matrix and the sensor probe by having a relatively low viscosity during the application process. Because.

Example 1
In accordance with the present invention, a Brabender mixer is equipped with 75.2 g vinylmethylsiloxane-octylmethylsiloxane-dimethylsiloxane copolymer, 25-30% methylhydrosiloxane-octyl sold under the trade name HAM301 by Gelest. 24.8 g of methylsiloxane copolymer (crosslinker with sterically hindered silicon hydride), 0.45 g of platinum carbonylcyclovinylmethylsiloxane catalyst marketed under the brand name SIP6829 by Gerest and trade name by Asahi Carbon of Japan Samples are prepared by charging 56.1 g of carbon black available under Asahi 15HS. These ingredients are mixed for 15 minutes at 25 ° C. to form a one-part matrix mixture.

  The sterically hindered silicon hydride crosslinker in the addition curable system of the present invention ensures a significantly longer pot life than the prior art. That is, the present invention makes it possible to mix together all the addition-curing polysiloxane precursors (siloxane having unsaturated hydrocarbon groups, cross-linking agent and catalyst having hydride) into a one-part addition curing system, This system has an industrially suitable pot life and allows the necessary processing to take place for a significant amount of time after mixing but before the production of the final crosslinked polysiloxane product. . That is, the present invention provides an economical method of producing polysiloxane compounds with a viable and effective one-part addition curing system.

  The descriptions and examples of the invention provided herein are merely exemplary and variations that do not depart from the spirit of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims (27)

(A) a siloxane reactant having at least one unsaturated organic functional group for the crosslinking reaction;
(B) a crosslinking agent comprising a silicon hydride group for the crosslinking reaction; and (c) at least one of the unsaturated organic functional group of the siloxane reactant and the silicon hydride of the crosslinking agent, comprising a catalyst. A one-component addition-curable polysiloxane system, both of which are sterically hindered.   The addition curable polysiloxane system of claim 1 wherein the unsaturated organic functional group of the siloxane reactant is sterically hindered.   The addition-curable polysiloxane system according to claim 1, wherein the silicon hydride of the crosslinking agent is sterically hindered. The sterically hindered silicon hydride group has the formula:

Wherein R ¹ and R ² each comprise a non-reactive organic group having 3 or more carbon atoms, independently from linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof In which R ³ , R ⁴ and R ⁵ are independently selected from the group consisting of non-reactive organic groups and hydrogen). Addition-curable polysiloxane system as described. The addition according to claim 4, wherein R ¹ and R ² are independently selected from the group consisting of propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, alkylphenyl, cyclopentyl and phenylpropyl. Curable polysiloxane system. R ¹ and R ² are, independently, butylated aryloxy propyl, N- methylpyrrolidone propyl, cyanopropyl, addition-curable poly according to claim 4 selected from the group consisting of benzyl trimethyl ammonium chloride, and hydroxyalkyl Siloxane system. The sterically hindered silicon hydride group has the formula:

Wherein R ¹ and R ² each comprise a non-reactive organic group having 3 or more carbon atoms, independently from linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof In which R ³ , R ⁴ and R ⁵ are independently selected from the group consisting of non-reactive organic groups and hydrogen). Addition-curable polysiloxane system as described. The addition according to claim 7, wherein R ¹ and R ² are independently selected from the group consisting of propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, alkylphenyl, cyclopentyl and phenylpropyl. Curable polysiloxane system. R ¹ and R ² are, independently, butylated aryloxy propyl, N- methylpyrrolidone propyl, cyanopropyl, addition-curable poly claim 7, selected from the group consisting of benzyl trimethyl ammonium chloride, and hydroxyalkyl Siloxane system. The sterically hindered silicon hydride group is a terminal group and has the formula:
[H (R ¹ R ² ) Si—O]-[(R ³ ₂ ) SiO] —
Wherein R ¹ and R ² each comprise a non-reactive organic group having 3 or more carbon atoms, independently from linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof 4. The addition-curable polysiloxane system according to claim 3, wherein each R ³ is selected from the group consisting of a non-reactive organic group and hydrogen. . The addition according to claim 10, wherein R ¹ and R ² are independently selected from the group consisting of propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, alkylphenyl, cyclopentyl and phenylpropyl. Curable polysiloxane system. R ¹ and R ² are, independently, butylated aryloxy propyl, N- methylpyrrolidone propyl, cyanopropyl, addition-curable poly claim 10 selected from the group consisting of benzyl trimethyl ammonium chloride, and hydroxyalkyl Siloxane system.   The addition according to claim 1, wherein the catalyst comprises a metal selected from the group consisting of ruthenium (Rh), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co) and mixtures thereof. Curable polysiloxane system. The catalyst is (PPh ₃ ) ₃ RhCl, [(C ₂ H ₄ ) ₂ RhCl] ₂ , (PPh ₃ ) ₃ RdCl ₂ , Rh ₂ (OAc) ₄ , Ru ₃ (CO) ₁₂ , Co ₂ (CO) The addition-curable polysiloxane system according to claim 1, comprising a compound selected from the group consisting of ₈ and platinumcarbonylcyclovinylmethylsiloxane.   The addition curable polysiloxane system of claim 1, wherein the siloxane reactant comprises a copolymer of polyoctylmethyldimethylsilicone. The siloxane reactant includes a vinylmethylsiloxane-octylmethylsiloxane-dimethylsiloxane copolymer, the unsaturated hydrocarbon functional group of the vinylmethylsiloxane-octylmethylsiloxane-dimethylsiloxane copolymer includes a vinyl group, and the crosslinking agent includes ,formula:

Wherein R ¹ , R ² and R ³ are each independently selected from the group consisting of a non-reactive organic group and hydrogen, wherein the catalyst comprises platinum carbonylcyclovinyl The addition curable polysiloxane system of claim 1 comprising methylsiloxane.   The addition curable polysiloxane system of claim 17 further comprising a plurality of conductive particles. A method for producing a polysiloxane polymer by one-component addition curing,
a) A siloxane reactant comprising a siloxane polymer having a functional group for crosslinking, a crosslinking agent having a silicon hydride functional group for crosslinking and a catalyst are mixed to form a one-part mixture, wherein the siloxane reactant At least one or both of the functional group and the silicon hydride of the crosslinking agent are sterically hindered,
b) causing a crosslinking reaction to occur between the siloxane reactant and the crosslinker component, wherein the sterically hindered functional group is a non-sterically hindered functional group and a non-sterically hindered silicon hydride functional group of siloxane. Reducing the rate of the crosslinking reaction compared to a comparative crosslinking rate.   19. The method of claim 18, wherein the step of performing the crosslinking reaction is completed at least about 24 hours after the mixing.   19. The method of claim 18, wherein the step of performing the crosslinking reaction is completed at least about 1 week after the mixing.   The method according to claim 18, wherein after the mixing, the one-component mixture is subjected to processing steps that are subjected to shearing, mixing, application, defoaming, casting, lamination, extrusion, pad printing, spraying, and silk screening.   The method of claim 21, wherein the processing step comprises applying the one-part mixture as a sensor film in a chemiresistor sensor. The silicon hydride functional group of the crosslinker component is sterically hindered and [H (R ¹ R ² ) Si—O] — [(R ³ ₂ ) SiO] —,

and

(Wherein R ¹ and R ² each comprise a non-reactive organic group having 3 or more carbon atoms, and the group consisting of linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof) R ³ , R ⁴ and R ⁵ are each independently selected from the group consisting of a non-reactive organic group and hydrogen. Addition-curing polysiloxane system.   The method according to claim 18, wherein the step of performing the crosslinking reaction is started by increasing the temperature of the one-part mixture.   The method of claim 24, wherein the temperature is increased from about 30 ° C to about 250 ° C. A method for producing a sensor film comprising:
a) a siloxane reactant having functional groups for cross-linking, a cross-linking agent containing silicon hydride functional groups for cross-linking, a catalyst and a plurality of conductive particles are mixed together to form a matrix mixture, wherein the siloxane At least one or both of the functional group of the reactant and the silicon hydride functional group of the crosslinker are sterically hindered;
b) reacting the siloxane reactant with the cross-linking agent in a cross-linking reaction, wherein the sterically hindered functional group of at least one or both of the siloxane reactant and cross-linking agent is a non-sterically hindered functional group of a siloxane comparison. The crosslinking reaction rate in the matrix mixture is reduced compared to the crosslinking reaction rate between the non-sterically hindered silicon hydride functional group of the crosslinking agent and
c) applying the matrix mixture to a sensor probe;
d) A method for producing a sensor film comprising producing a polysiloxane matrix product. The silicon hydride of the crosslinking agent is sterically hindered,
[H (R ¹ R ² ) Si—O]-[(R ₂ ) SiO] —

Wherein R ¹ and R ² each comprise a non-reactive organic group having 3 or more carbon atoms, independently from linear alkyl, branched alkyl, aryl, aromatic, and mixtures thereof R ³ , R ⁴ and R ⁵ are each independently selected from the group consisting of non-reactive organic groups and hydrogen) nominally selected from the group consisting of 27. The method of claim 26, represented by a formula.